Bug#948277: Certbot wiki suggests using main repo instead of backport repo for Stretch

[Bastian Stassen]

https://wiki.debian.org/LetsEncrypt <https://wiki.debian.org/LetsEncrypt>
says:

Stretch (Debian 9.x) / Buster (Debian 10.x) / Testing / Unstable Howto:

You can install certbot from the main repository.



So maybe we should now remove the backport repo from apt-get sources and try to 
upgrade certbot?


Bart